In that patent specification there was disclosed a pump wherein the plurality of circumferentially spaced arms were driven within a cylindrical housing, and between adjacent arms there were arranged flaps which pivoted about axial pivots to vary the displacement volume between the flaps and the inner surface of the housing, the degree of pivoting being controlled by eccentricity of a ring coupled to those flaps by respective links. Each link was pivoted at its radially outer end to a respective flap, and all but one was pivoted to a ring, the one which was not pivoted being an extension of the ring fixed with respect to the ring. Although searches have been made, the Applicant knows of no other prior art pump which utilises that principle.
Pumps made in accordance with that patent have proved particularly successful technically for pumping many materials which are otherwise difficult to pump, and very efficient in that the horse power requirement for pumping a volume at a rate was less than with most other pumps, for example, about half that required for a centrifugal pump wherein a great deal of fluid friction is developed.